Dental Research Journal
Volume:20 Issue: 8, Aug 2023

Chairside fabrication of provisional restorations using three‑dimensional (3D) printers is rising in digital dentistry. The purpose of this research was to compare the marginal and internal adaptation of provisional polymethyl methacrylate (PMMA) restorations fabricated by two different 3D printers.

In this in vitro investigation, an intact maxillary 1st molar acrylic model was first digitalized by a laboratory scanner. It was then prepared for an all‑ceramic restoration and scanned again by the same scanner. The final restoration was designed in Exocad according to the scan files with a 50 μm cement gap. PMMA restorations were printed by two 3D printers; Group 1: Asiga (n = 10) and Group 2: Digident (n = 10). The replica technique was used to assess the marginal and internal fit of the restorations, and one‑way ANOVA was used to analyze the data. P <0.05 was regarded as statistically significant.

The mean marginal gap of crowns in Group 1 was significantly lower than that of Group 2 (75 vs. 195 μm, P = 0.001). Regarding internal adaptation, no significant difference was found between the axial gap values in both groups (P > 0.05). The mean occluso‑axial gap (90 vs. 140 μm, P = 0.026) and the mean occlusal gap (116 vs. 300 μm, P = 0.001) of crowns in Group 1 were significantly smaller compared to the equivalent values in Group 2.

Provisional PMMA crowns fabricated by the Asiga printer showed significantly higher marginal and internal adaptation than those manufactured by Digident at all points except for the axial surface.

This study aims to investigate the color stability of feldspathic porcelains with different concentrations of silver nanoparticles (AgNPs).

In this experimental study, feldspathic porcelain disks with AgNPs of 0 parts per million (ppm), 250 ppm, and 500 ppm were used (sample size = 180). These ceramic discs were subjected to thermocycling in tea, orange juice, and artificial saliva. The optical parameters of disks were measured before and after being immersed in the solutions. Then, the color change (ΔE 00) of the samples was measured by using the CIEDE 2000 formula. The data were analyzed by one‑way analysis of variance (ANOVA) and Tukey’s post hoc test. The level of significance was determined to be 0.05.

The results of the ANOVA test show that there was a significant difference in ΔE 00 (P ≤ 0.05). The maximum ΔE 00 was visible in the samples with AgNPs 0 ppm that were exposed to orange juice, and the minimum ΔE 00 was related to the disks with AgNPs 500 ppm in artificial saliva.

Based on the results of this study, adding AgNPs to feldspathic porcelain increases the color stability of the ceramic discs.

This study assessed the diagnostic accuracy of cone‑beam computed tomography (CBCT) with a modified grayscale range for the detection of buccal cortical plate defects adjacent to dental implants.

In this in vitro experimental study, titanium implants were inserted in 168 fresh bovine bone blocks with 1–1.5 mm of buccal cortical plate thickness. The blocks were randomly divided into four groups (n = 42). No defect was created in the control blocks. In the three experimental groups, cortical plate defects were randomly created in the cervical, middle, or apical third by a round bur with a 2‑mm diameter (n = 42). All blocks underwent CBCT with and without change in the grayscale range. Two observers evaluated all images regarding the presence/absence of defects. Kappa test is used for the agreement of the observers. The diagnostic accuracy of the two modalities was compared by calculating the area under the receiver operating characteristic curve (AUC) (P ≤ 0.05). The sensitivity and specificity values were also compared.

The AUC was not significantly different between the two modalities with and without altered grayscale range (0.754 vs. 0.762, respectively, P = 0.716). The diagnostic sensitivity of CBCT with and without change in the grayscale range was 51% and 52%, respectively, with a specificity of 100% for both. The diagnostic accuracy of CBCT with and without altered grayscale range had no significant difference for apical and middle third defects (P > 0.05) and was significantly higher than that for the cervical third defects (P < 0.05).

Changing the grayscale range does not improve the diagnostic accuracy of CBCT for the detection of buccal cortical plate defects adjacent to dental implants.

This study aimed to compare the effects of laser photodynamic therapy (PDT) with methylene blue (MB) or aminolevulinic acid (ALA) on the oral squamous cell carcinoma (OSCC) cell line.

In this in vitro experimental study, the C152 (KB) OSCC cell line was cultured in a culture medium containing 10% fetal bovine serum. The cells were exposed to 0.1, 0.2, 0.5, 1, 2, 5, and 10 mM concentrations of MB and ALA alone and combined with diode laser irradiation with 660 nm wavelength, 40 mW power, and 10 J/cm2 energy density in continuous‑wave mode perpendicular to the surface. Cell viability was assessed using the methyl thiazolyl tetrazolium assay and compared among the groups by the Kruskal–Wallis test.

The results showed that the reduction in cell viability in the MB + laser and ALA + laser groups was greater than that in the MB and ALA groups without laser (P < 0.001). Significant differences were noted in cell viability in the presence of some different concentrations of MB and ALA (P < 0.05), such that by an increase in their concentration, cell viability decreased. Cell viability in the MB + laser group was significantly lower than that in the ALA + laser group in some photosensitizer concentrations (P < 0.05).

Within the limitations of this in vitro study, the results showed that laser PDT with MB (high concentrations) was more effective than laser PDT with ALA against the OSCC cell line.

Shock wave‑enhanced emission photoacoustic streaming (SWEEPS) is a novel irrigation activation method based on photoacoustic streaming. The aim of this study was to look into the impact of SWEEPS on the attachment and survival of dental pulp stem cells (DPSCs).

In this in vitro study, 34 standardized root segments were randomly allocated into two groups: SWEEPS and the conventional conditioning group. After the irrigation, human DPSCs were seeded on the internal walls of these samples, and the attachment and survival of 30 of them were assessed on different days. The remaining two samples were observed using a scanning electron microscope (SEM). Independent sample t‑test, Mann–Whitney U‑test, one‑way ANOVA, Kruskal–Wallis, and two‑way ANOVA were used for data analysis with the level of significance = 0.05.

The viability of DPSCs was significantly greater in the SWEEPS group in comparison with the conventional conditioning group (P = 0.029). Both groups have shown a significant increase in the viability of DPSCs over time (P = 0.0001, P = 0.003). SEM results have shown a smear layer‑free surface with firmly attached DPSCs in the SWEEPS group.

The results of this study indicated that active irrigation using SWEEPS could provide a superior surface in terms of viability and attachment of DPSCs compared to the conventional conditioning method.

Diagnosis of dental caries using cone‑beam computed tomography (CBCT) may be hindered due to several introduced and inherent artifacts. The aim of this study was to evaluate the effect of amalgam fillings on the accuracy of diagnosis of proximal caries in CBCT.

In this in vitro study, 102 extracted human teeth (mandibular and maxillary molars and premolars) were used. Six molars were chosen for mesio‑occluso‑distal amalgam restorations. Before obtaining the CBCT images, the 96 remaining teeth were stabilized in dental sockets of six dry human skulls in a way that the proximal contacts re‑established. Thereafter, six of the molar teeth were replaced by the amalgam‑restored teeth and the second group of images was then obtained. All images were evaluated by two independent observers in the panorama view and the presence or absence of caries was recorded. For histopathologic investigations, the teeth were cut and assessed by an oral pathologist using a stereomicroscope. The McNemar test was used for comparison between CBCT assessments and histopathologic evaluations (P < 0.05 was considered statistically significant). In addition, the receiver operating characteristics curve was utilized to evaluate the diagnostic accuracy in different sections of imaging.

The result sensitivity and specificity of CBCT imaging in the first group of images before placement of the restored teeth were 0.96 and 0.36, respectively. In the second group of images after placement of the restored teeth, these values were 0.78 and 0.18, respectively. Moreover, statistical analysis showed that there is a good agreement in interproximal caries diagnosis between histopathologic and CBCT imaging findings without placement of amalgam restorations (P < 0.001). However, this agreement does not exist after amalgam restorations (P = 0.84).

Diagnosis of proximal caries using CBCT is not an efficient method where there are amalgam restorations adjacent to the suspected teeth.

Since general dentists (GDs) usually act as the primary referral source for the patients in need of orthodontic treatments, having the proper knowledge and understanding of the accurate diagnosis of clinical situations is very important. The aim of this study was to assess GDs about the identification of orthodontic treatment needs and their referral practices.

This descriptive and analytical cross‑sectional study was carried out in Iran 2020. A questionnaire consisting of three main parts was designed and distributed electronically among GDs. The first section included 11 image and scenario‑based questions meant to assess the ability of GDs to correctly diagnose the orthodontic treatment needs of the patients. The next two parts were to assess the dentists’ knowledge of the necessity of referral to an orthodontist with 11 questions, and the proper timing of orthodontic treatments with 8 questions. Data were analyzed using SPSS 26, by conducting Mann–Whitney, Kruskal–Wallis, and correlation tests α = 0.05.

Among 384 participated dentists, 50.3% (193) were female. The mean score of knowledge was 17.3 ± 3.5 out of 30. The highest percentage of good knowledge (70% of range) was related to the diagnosis of orthodontic problems, while the lowest one belonged to the referring pattern. There was a weak positive correlation between the working experience and the proper timing of referral (R = 0.15, P = 0.004 (. Kruskal–Wallis test also showed a significant difference between the total knowledge scores (P = 0.04) and the knowledge of the proper timing of treatment (P = 0.04) based on the age groups of participants. Eighty‑seven percentage (n = 334) reported that they would refer the patients in need of orthodontic treatment.

The knowledge level of orthodontic treatment needs among GDs was moderate, thus emphasizing the importance of planning more educational courses for them to improve their knowledge, thus reducing the possible detriments of postponed or inaccurate treatments.

Root canal obturation is an important step in endodontic treatment, which is performed aiming to three-dimensionally seal the canal and prevent microleakage, reentry, and proliferation of microorganisms in the root canal system. On the other hand, microleakage eventually leads to root canal treatment failure. Sealing ability is an important property of endodontic sealers. This in vitro study aimed to compare the quality of apical seals obtained by three endodontic sealers.

This in vitro experimental study evaluated 48 extracted single-canal maxillary incisors. Hard- and soft-tissue residues were removed and the teeth were immersed in 5.25% of sodium hypochlorite for disinfection. The teeth were decoronated at the cementoenamel junction with a diamond disc such that 10 mm of root length remained. Canal patency was ensured using a #10 K-file. The canals were then instrumented with ProTaper rotary system. The canals were randomly divided into three experimental groups for the application of Adseal, Proseal, and AH26 sealers, and positive and negative control groups. Sealers were applied in the canals using lateral compaction technique. The external root surfaces were then coated with two layers of nail varnish except for the apical 3 mm. The amount of microleakage was quantified using the dye-penetration technique. The Tukey’s test was used to compare the microleakage between the experimental and control groups. The Kruskal–Wallis test was applied to compare the microleakage of experimental groups (P < 0.05).

The amount of microleakage in canals filled with Adseal, Proseal, and AH26 sealers with lateral compaction technique was 2.33 ± 0.64, 2.2 ± 0.81, and 2.22 ± 0.71 μm, respectively. No significant difference was noted among the three sealers regarding microleakage (P = 0.84). However, the amount of microleakage in the sealer groups was significantly lower than that in the control group (P < 0.001).

The application of Adseal, Proseal, and AH26 had equal efficacy for the provision of optimal apical seal in filling of root canals with lateral compaction technique. The application of sealers yielded a significantly superior apical seal compared with the control group.

In general, bioactive glasses (BAGs) can react with tissue minerals and promote remineralization. However, the application of BAG in bonding agents and its impact on bond strength remain uncertain due to insufficient information and limited research in this area.

This study employed a randomized controlled design to assess the effects of composite‑bonding agents with varying BAG contents on shear bond strength and fracture pattern in sound and demineralized teeth, with and without thermocycling. Thus, 80 healthy third molars were randomly divided into two groups: sound teeth and demineralized teeth. Five bonding agents were applied to the prepared dentin surfaces, including four experimental composite‑bonding agents with varying BAG content (0, 0.2, 0.5, and 2 wt%) and the Adper Single Bond commercial bonding as control. The shear bond strength of all samples was measured using a universal tester. The type of failure of each specimen was determined using a stereomicroscope. Kruskal–Wallis nonparametric test was performed on the obtained shear bond strength data followed by Mann–Whitney post hoc test with Bonferroni correction to determine statistical significance. The level of significance was considered P ≤ 0.05 for all tests and was adjusted by Bonferroni correction.

Demineralization significantly decreased shear bond strength in the teeth samples. Adper Single Bond exhibited the highest shear bond strength values. The addition of BAG did not have a significant influence on shear bond strength, regardless of demineralization or thermocycling condition. Adhesive failure was the predominant type of failure in all groups.

The incorporation of BAG filler up to 2 wt% did not result in significant changes in shear bond strength. Experimental adhesive bonding agents with 2 wt% BAG content demonstrated shear bond strengths comparable to the commercial bonding agent in sound nontreated, sound thermocycled, demineralized nontreated, and demineralized thermocycled groups.

Carnitine is effective in preventing the accumulation of end products related to lipid peroxidation due to its anti‑inflammatory and antioxidant effects. Carnitine also exerts a significant anti‑inflammatory role through the downregulation of the nuclear factor kappa beta pathway, which leads to a decrease in the expression of pro‑inflammatory cytokines.The aim of the study was to estimate the L‑carnitine (L‑C) levels in diabetic completely edentulous patients.

A cross‑sectional study was conducted after the selection of 60 samples based on the inclusion and exclusion criteria. The collected saliva samples were utilized to measure the levels of L‑C using the sandwich enzyme‑linked immunosorbent assay (ELISA) method. One hundred microliters of sample was applied to a particular row of wells and incubated for an hour as part of the sandwich ELISA procedure. After the wells had been cleaned, a second batch of monoclonal L‑C was added, and they were once more incubated for an hour. The horseradish peroxidase substrate was then applied after washing the second batch as well. To allow the blue‑to‑yellow color transition, the wells were kept steady. Following the observation of the color shift, the OD was measured, and the concentration was determined using the sandwich ELISA kit’s standard curve as an intercept. The data were statistically analyzed using the independent t‑test (significant level P < 0.05) and were tabulated.

The L‑C levels have higher levels in nondiabetic patients than in diabetic patients. The difference in the baseline mean value between the groups was statistically significant (P = 0.00). Although it is statistically significant (P = 0.00), the mean value for diabetic individuals is 0.19 as opposed to 0.29 for nondiabetic patients.

Based on the findings, it can be concluded that L‑C improves insulin sensitivity and glucose disposal in diabetic completely edentulous patients.